The influence of radiotherapy treatment time on the control of laryngeal cancer: a direct analysis of data from two British Institute of Radiology trials to calculate the lag period and the time factor.
AffiliationBiomathematics and Computing Unit, Paterson Institute for Cancer Research, Manchester, UK.
MetadataShow full item record
AbstractThis study analyses node-negative laryngeal tumour control data from two clinical trials conducted by the British Institute of Radiology in order to determine the time factors and the presence or absence of a lag period before the time factor takes effect. A direct maximum likelihood approach is used to fit a double-logarithmic model including a repopulation term which commences after an initial lag period, Tk. The analysis yields a time factor of 0.8 Gy per day (95% confidence interval 0.5-1.1 Gy per day) as the extra dose required to counteract the reduction in tumour control probability (TCP) with extension of the treatment time. The latter reduction amounted to between 5 and 12% TCP per week, depending on the stage and time period. With this dataset, where few patients were treated for short times, no statistically significant lag phase can be demonstrated. However, the best estimate of Tk is 21 days (95% confidence interval 0-27 days), which is consistent with estimates from other studies on other datasets. If a lag phase exists, this study would indicate that the duration is less than 27 days. Other studies have used retrospective data and are subject to a number of potential biases. The present study, using data from multicentre prospective randomized clinical trials, is free from some of these sources of bias. The fact that very similar estimates of the radiobiological parameters are obtained lends credence to these other studies and suggests that the potential biases may be small in practice.
CitationThe influence of radiotherapy treatment time on the control of laryngeal cancer: a direct analysis of data from two British Institute of Radiology trials to calculate the lag period and the time factor. 1994, 67 (800):790-4 Br J Radiol
JournalThe British Journal of Radiology
- Further analysis of radiobiological parameters from the First and Second British Institute of Radiology randomized studies of larynx/pharynx radiotherapy.
- Authors: Chappell R, Nondahl DM, Rezvani M, Fowler JF
- Issue date: 1995 Sep 30
- First interim progress report on the second British Institute of Radiology Fractionation Study: short versus long overall treatment times for radiotherapy of carcinoma of the laryngopharynx.
- Authors: Wiernik G, Alcock CJ, Bates TD, Berry RJ, Brindle JM, Dalby JE, Fowler JF, Gajek WR, Goodman S, Haybittle JL
- Issue date: 1989 May
- Time factors in larynx tumor radiotherapy: lag times and intertumor heterogeneity in clinical datasets from four centers.
- Authors: Roberts SA, Hendry JH
- Issue date: 1999 Dec 1
- Modelling the optimal radiotherapy regime for the control of T2 laryngeal carcinoma using parameters derived from several datasets.
- Authors: Roberts SA, Hendry JH, Slevin NJ
- Issue date: 1997 Dec 1
- Sensitivity of human squamous cell carcinoma of the larynx to fractionated radiotherapy.
- Authors: Rezvani M, Fowler JF, Hopewell JW, Alcock CJ
- Issue date: 1993 Mar